Rb20/rb26 intake

[Js_skyline]

Aight so I have my intake now an am gonna be cutting my stock rb20 intake on the runners an mating it to my rb26 intake plenum. Now I'm curious how long will I want to have my runners so I have a happy balance of high an low end power? An how much will My stock 63mm throttle body flow? I'm only really shoot for 400 horse an don't know if it worth doing the 90mm q45.
Cheers.

[Js_skyline]

Anyone? I'm getting this done soon an don't want to screw it up. Any input would be great.
Cheers

[nimblestix]

This isn't a common mod, so I don't think there's much for input out there. Best of luck. I will say however I think 90mm is going to be overkill. I'd go for 80mm largest.

[Js_skyline]

Ahh ok thanks. So I'll just wing it an see how it goes. I'm thinking I'm just going to use my stock tb

[Skym]

Stock RB20DET intake plenum was good for around 500hp at engine with Group-A RB20DET engines.

Just need better intake gaskets and Cometic sell those.

There's no point in changing the intake plenum for a 400hp RB20DET.

This is a R32 RB20DET in Canada with 480hp at engine with stock intake plenum, basic boost up mods -

https://www.youtube.com/watch?v=X_mibuiFSuk

Probably would be an easy 500hp+ engine with Tomei Poncams, adjustable cam gears which helps to spool the turbo earlier.

If above 500hp I would look into fitting stock GTR intake plenum, throttle bodies with a CNC adaptor plate between head, throttle bodies (better response with GTR intake plenum).

[Js_skyline]

I'm mostly going for looks. I really hate how the stock plenum goes over the motor. So I'm cutting my intake at the runners just after the injectors seats am having the gtr intake welded to my runners an cutting off my throttle body flange an welding it to the inlet on the gtr plenum. I seen it done on the skylineaustralia forum. I'm also gonna be using a rb26 power fc on my rb20 as well to tune.

[Bee-RSkyline]

I'm running the RB26 manifold on my RB20, but running the ITB's instead of the stock RB20 throttle body.
No real gains from what I can tell, but the engine bay sure looks cleaner.